Impact of restless legs syndrome and iron deficiency on attention-deficit/hyperactivity disorder in children

Sleep Med. 2007 Nov;8(7-8):711-5. doi: 10.1016/j.sleep.2007.04.022. Epub 2007 Jul 20.


Objective: Increasing evidence suggests a significant comorbidity between attention-deficit/hyperactivity disorder (ADHD) and restless legs syndrome (RLS). Iron deficiency may underlie common pathophysiological mechanisms in subjects with ADHD plus RLS (ADHD+RLS). To date, the impact of iron deficiency, RLS and familial history of RLS on ADHD severity has been scarcely examined in children. These issues are addressed in the present study.

Methods: Serum ferritin levels, familial history of RLS (diagnosed using National Institutes of Health (NIH) criteria) and previous iron supplementation in infancy were assessed in 12 ADHD+RLS children, 10 ADHD children and 10 controls. RLS was diagnosed using NIH-specific pediatric criteria, and ADHD severity was assessed using the Conners' Parent Rating scale.

Results: ADHD symptom severity was higher, although not significantly, in children with ADHD+RLS compared to ADHD. The mean serum ferritin levels were significantly lower in children with ADHD than in the control group (p<0.0005). There was a trend for lower ferritin levels in ADHD+RLS subjects versus ADHD. Both a positive family history of RLS and previous iron supplementation in infancy were associated with more severe ADHD scores.

Conclusions: Children with ADHD and a positive family history of RLS appear to represent a subgroup particularly at risk for severe ADHD symptoms. Iron deficiency may contribute to the severity of symptoms. We suggest that clinicians consider assessing children with ADHD for RLS, a family history of RLS, and iron deficiency.

MeSH terms

  • Anemia, Iron-Deficiency / complications*
  • Anemia, Iron-Deficiency / epidemiology*
  • Attention Deficit Disorder with Hyperactivity / diagnosis
  • Attention Deficit Disorder with Hyperactivity / epidemiology*
  • Attention Deficit Disorder with Hyperactivity / etiology*
  • Child
  • Child, Preschool
  • Comorbidity
  • Dopamine / blood
  • Electronic Data Processing
  • Female
  • Ferritins / blood
  • Humans
  • Male
  • Prevalence
  • Restless Legs Syndrome / diagnosis
  • Restless Legs Syndrome / epidemiology*
  • Restless Legs Syndrome / etiology*
  • Severity of Illness Index


  • Ferritins
  • Dopamine